(a) Representative Raman spectra of the Si1 − x Ge x as-grown samples with and the Raman intensity plotted in logarithmic scale. (b) Representative spectra of the as-grown sample with and for different annealing temperatures. Peak assignment to the alloy optical Raman modes is indicated.
Out-of-plane lattice parameter ( ) of the SiGe alloy layers determined by XRD measurements as a function of the annealing temperature for samples A to E. The vertical line corresponds to the as-grown samples. Error bars of the data points are around Å.
Three dimensional plots showing the solutions of Eqs. (8) and (9) for the Ge-Ge (violet) and Si-Si (orange) modes, respectively. In panel (a), we show the two surfaces for the as-grown sample E. The same surfaces are shown in (b) for sample E after all the annealing sequences. The physically reasonable solutions are given by the intersection of the two dimensional surfaces as marked with a white line.
Solutions of Eqs. (8) and (9) for all the as-grown samples (solid lines) and annealed ones (circled lines) represented in the plane. The dotted black lines connect points with constant values of compositional inhomogeneity degree , representing real solutions, whereas the grey dotted lines are a guide to the eye, representing estimated solutions.
Si1− x Ge x alloy-layer thickness (d) of the different samples determined by spectral ellipsometry. Ge content for the as-grown layers obtained from XRD measurements (xxrd ) and using the model discussed in Sec. IV B (xmodel ). Numbers in parentheses represent error bars.
Composition dependence of the strain shift coefficients for the Ge-Ge, Si-Ge, and Si-Si modes extracted from Ref. 24 . Lattice constants and elastic constants extracted from Refs. 32 and 33 , respectively. The polynomial parameters for the unstrained frequencies were obtained by a combined fit to the data of Refs. 28 and 34 .
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